docs: def radiance2tb(self, rad):
          """Get the Tb from the radiance using the simple non-linear regression
          method.
  
          rad: Radiance in units = 'mW/m^2 sr^-1 (cm^-1)^-1'
  
          """
          #
          # Tb = C2 * νc/{α * log[C1*νc**3 / L + 1]} - β/α
          #
          # C1 = 2 * h * c**2 and C2 = hc/k
          #
          c_1 = 2 * H_PLANCK * C_SPEED ** 2
          c_2 = H_PLANCK * C_SPEED / K_BOLTZMANN
  
          vc_ = SEVIRI[self.bandname][self.platform_name][0]
          # Multiply by 100 to get SI units!
          vc_ *= 100.0
          alpha = SEVIRI[self.bandname][self.platform_name][1]
          beta = SEVIRI[self.bandname][self.platform_name][2]
  
          tb_ = c_2 * vc_ / \
              (alpha * np.log(c_1 * vc_ ** 3 / rad + 1)) - beta / alpha
  
          return tb_